Ondem Injection
Ondem Injection (Ondansetron 2 mg/ml, 4 mg per 2 ml ampoule) — hospital-administered IV/IM 5-HT3 antagonist for chemotherapy, radiation, and post-operative nausea. Alkem generic of Zofran injection.
✓ Medically reviewed by Morgan Ellis — Pharmacy Researcher · 8 years experience · Last reviewed: May 2026
⚡ Quick Answer — What is Ondem Injection?
Ondem Injection contains ondansetron 2 mg/ml in 2 ml ampoules (4 mg total) — a selective serotonin 5-HT3 receptor antagonist used in hospitals to prevent and treat chemotherapy-induced, radiation-induced, and post-operative nausea and vomiting (PONV). Administered by a healthcare professional intravenously (slow push or short infusion) or intramuscularly. Onset within 5–10 minutes IV. Manufactured by Alkem Laboratories — the generic equivalent of Zofran injection. FDA single-dose cap 16 mg IV due to QT signal at higher doses.
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Our generic medications are sourced from WHO-GMP certified manufacturers and shipped worldwide in discreet, plain packaging — no medication name on the parcel exterior. Card payments are routed through a regulated processor (statement descriptors include a regulated card-payment processor — never “MedsBase” or any medication name). Crypto and SEPA bank transfer are also accepted. Every order is backed by our Reshipment Assurance Policy.
Why order from MedsBase
Ondem Injection is supplied from a WHO-GMP certified manufacturer. Every order ships discreetly worldwide and is covered by our Reshipment Assurance Policy — if it does not arrive within 20 business days, we reship at no cost. Ondem Injection is the global standard parenteral 5-HT3 antagonist for inpatient antiemesis. Alkem is one of India’s largest WHO-GMP injectable manufacturers and the formulation is bioequivalent to the reference brand.
Mechanism of action
Chemotherapy, radiation, and surgical stress damage gut enterochromaffin cells, releasing massive amounts of serotonin (5-HT). The serotonin binds 5-HT3 receptors on vagal afferents and on the chemoreceptor trigger zone (area postrema), generating the strongest known oral/intestinal emetic stimulus. Ondansetron is a highly selective antagonist at the 5-HT3 receptor — it interrupts this signal at both peripheral and central sites without affecting D2, H1, muscarinic, or alpha-adrenergic receptors. The clean receptor profile explains the absence of sedation, extrapyramidal reactions, and anticholinergic side effects that limit older antiemetics like prochlorperazine and metoclopramide.
Indications
- CINV: moderately or highly emetogenic chemotherapy — usually with dexamethasone ± aprepitant for highly emetogenic regimens.
- Radiation-induced nausea: total body irradiation, high-dose abdominal/pelvic radiation.
- Post-operative nausea and vomiting (PONV): single 4 mg dose at induction or end of surgery; prophylaxis for high-risk patients (Apfel score ≥ 2).
- Severe gastroenteritis in patients unable to retain oral fluids.
- Refractory hyperemesis gravidarum — second/third-line after doxylamine+B6 and metoclopramide.
Dose
| Indication | Dose |
|---|---|
| CINV (highly emetogenic) | 8 mg slow IV (over > 15 min) 30 min before chemo, then 8 mg every 4 h × 2 doses, then transition to oral 8 mg every 12 h |
| CINV (moderately emetogenic) | 8 mg slow IV 30 min before chemo, then transition to oral |
| PONV (adult) | 4 mg slow IV at induction or end of surgery (single dose); some protocols 8 mg for high-risk |
| Paediatric (CINV) | 5 mg/m² IV before chemo (max 8 mg per dose); weight-based for gastroenteritis |
| Single-dose maximum | 16 mg IV (FDA cap due to QT signal); slow IV push over 30 sec or short infusion 15 min |
| Severe hepatic impairment | Maximum 8 mg/day (Child-Pugh C) |
Compatible with 0.9% sodium chloride and 5% dextrose; do not mix in the same syringe with other drugs. Administer slow IV (over 30 seconds for push or 15 min for infusion) — rapid bolus increases the QT signal.
Side effects
- Common: headache (often within minutes of injection), constipation, mild flushing, transient AST/ALT rise, fatigue
- Less common: dizziness, hot flushes, hiccups, mild bradycardia, hypotension after rapid IV
- Rare but serious: QT prolongation/torsades (especially with single doses > 16 mg), serotonin syndrome (with SSRIs/SNRIs/triptans), severe hypersensitivity, transient blindness (very rare), arrhythmia
- Uncommon: extrapyramidal reactions (rare with ondansetron unlike older antiemetics)
Drug interactions
- Apomorphine: ABSOLUTE contraindication — severe hypotension and loss of consciousness reported.
- Other QT-prolonging drugs (azithromycin, clarithromycin, citalopram, escitalopram, methadone, amiodarone, sotalol, fluoroquinolones, hydroxychloroquine, antipsychotics): avoid combination or monitor ECG.
- Serotonergic drugs (SSRIs, SNRIs, MAOIs, triptans, tramadol, fentanyl, linezolid, methylene blue): rare serotonin syndrome reported.
- Strong CYP3A4 inducers (rifampicin, phenytoin, carbamazepine): may lower ondansetron levels and reduce efficacy.
- Tramadol: ondansetron may reduce tramadol analgesic effect (5-HT3 blockade interferes with descending pain inhibition).
Frequently Asked Questions
How quickly does Ondem Injection work?
Onset is within 5–10 minutes after slow IV push and 15–30 minutes after IM injection. Antiemetic effect lasts 8–12 hours. The IV form is preferred for active vomiting where oral routes are unreliable.
Why is the IV ondansetron dose capped at 16 mg?
FDA review of cardiac safety data found that single IV doses > 16 mg significantly increase the risk of QT prolongation and torsades-de-pointes. The 16 mg cap applies to single doses; total daily dose can still be 24 mg given as 8 mg every 8 hours.
Can Ondem Injection be given IM?
Yes — IM is a reasonable route when IV access is difficult, with onset 15–30 minutes (slower than IV but faster than oral). The standard IM dose is 4 mg; do not exceed 16 mg per single dose.
Can Ondem Injection be used in pregnancy?
Reserved for refractory hyperemesis gravidarum after doxylamine+B6 and metoclopramide have failed. Some observational studies suggest a small first-trimester cardiac and cleft-palate signal — weigh against the maternal risk of severe untreated hyperemesis. Specialist supervision recommended.
Is Ondem Injection safe in children?
Yes — weight or BSA-based dosing is well established for paediatric chemotherapy and severe gastroenteritis. The dose is typically 5 mg/m² IV before chemo (max 8 mg) or weight-based (0.15 mg/kg) for gastroenteritis.
Why does Ondem Injection cause constipation?
5-HT3 receptors in the gut wall regulate gut motility — blocking them reduces peristalsis and slows colonic transit. Constipation is the most clinically meaningful side effect; pre-empt with hydration, fibre, and prophylactic laxatives during multi-day chemo courses.
Does Ondem Injection cause sedation?
No. Unlike promethazine, prochlorperazine, and metoclopramide, ondansetron does not cause sedation, extrapyramidal reactions, or anticholinergic side effects.
Can Ondem Injection be mixed with chemotherapy in the same line?
Ondansetron is incompatible with several chemotherapy agents in the same syringe; flush the line with normal saline between drugs. Compatibility is product-specific and should be checked against pharmacy guidelines for each chemotherapy combination.
What if a single dose > 16 mg is needed?
For highly emetogenic chemotherapy, give 8 mg slow IV every 4 hours rather than a single high dose. Switching to a different 5-HT3 (granisetron, palonosetron) or adding an NK1 antagonist (aprepitant) is usually a better strategy than exceeding the 16 mg single-dose cap.
How is Ondem Injection stored?
Store ampoules at room temperature (15–25°C), protect from light. Do not freeze. Inspect the solution before use — it should be clear and colourless.
Other Nausea Treatments
- Ondem (ondansetron oral tablet — oral switch after IV)
- Emeset 4 ODT (oral disintegrating — transition from IV)
- Granicip (granisetron — once-daily 5-HT3)
- Dompewal (domperidone — alternative class)
- Stemetil MD (prochlorperazine ODT — rescue antiemetic)
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| Strength | 2 ml |
|---|---|
| Quantity | 10 Ampoule/s, 20 Ampoule/s, 30 Ampoule/s, 60 Ampoule/s |
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